The present invention relates to fluid dispensing devices and methods for printing on spinning circular media. More particularly, it concerns mechanisms for placing ink on spinning circular media discs.
In the art of dispensing fluidic ink objects as it applies to radial printing, there is a need to place ink objects efficiently onto the spinning circular media to effectively use the mechanisms of radial printing. Radial printing generally includes dispensing ink onto a media at a particular radius of the media while the media is rotating. Additional challenges exist with physical limitations and interactions of the devices employed, such as with the fluid dispensing device, herein alternately termed xe2x80x9cprint penxe2x80x9d or xe2x80x9cpen,xe2x80x9d wherein the maximum frequency of the pen""s firing cycle, in terms of both the pen""s overall fluid firing capacity and recovery time, increase proportionally as spinning rates of CD devices increase.
Commercially available ink jet print pens have inherent limitations as it relates to media spin rates, or in other words, the speed at which the surface to be printed moves past the pen. Two limitations are factors in maximizing print speed of a device using these devices:
(1) The pen recovery latency, after firing, to allow time for the meniscus to recover and the pen ink well to refill, and
(2) The maximum pen firing frequency, at which the pen can repetitively fire a burst of nozzles.
For example, a typical ink jet has a pen firing frequency of 12 kHz and a pen recovery time of about 83 xcexcs, which is adequate to keep pace and print the media consecutively printing 20,480 instantaneous angular counts per rotation for up to about the normal 2xc3x97 CD media spinning rates of 720 RPM. With even higher rotation speeds, the required pen firing frequencies to print consecutively on the media exceed the capability of the pen.
In other words, the pen""s firing frequency and pen recovery latency is currently a limiting factor in the speed that can be achieved in radial printing, wherein CD rotation speeds may substantially exceed the pen""s capabilities. In view of the foregoing, there is a need to solve the unique problems associated with printing on a spinning CD. Additionally, printing mechanisms for overcoming a ink pen""s firing frequency are needed.
Accordingly, the present invention provides mechanisms for increased radial printing speeds without a requirement to increase the pen""s frequency capability, thus enabling the use of standard commercially available pens in radial printing devices.
The present invention includes several embodiments for placing ink on spinning circular media to solve problems with physical printing limitations, such as pen maximum frequency and pen recovery latency as spinning rates increase. Normal inkjet pen frequency is adequate to keep pace with instantaneous angular velocities for up to twice the spinning media spinning rates. However, with higher rotation speeds, the required pen frequencies can exceed the capability of the pen. Thus, mechanisms are provided in which printing may be accomplished without a requirement to increase the pen frequency capability.
In general terms, this invention uses interleaved radial printing to solve a problem inherent to optimizing the printing time and addresses physical printing limitations, such as pen maximum frequency and pen recovery latency time while printing to spinning circular media. Interleaved radial printing generally includes shifting the firing time to when the print pen is directly over the area to be printed, which herein will be called the xe2x80x9ctarget sector.xe2x80x9d The print pen is activated at a particular time to produce best results, which herein will be called the xe2x80x9cfiring zone,xe2x80x9d which can be visualized as an arch-shaped swath of a limited angular length on the surface of the rotating circular media.
The present invention provides one or more of the following mechanisms to remedy the above and other issues related to radial printing on rotating circular media through the use of interleaved radial printing:
In one general embodiment, the print pen is given shorter band of data to print, interspersed on the same track, which is at the same radial position on the media. In this situation, interleaving operates such that the print pen reprints in more than one rotation: at one and a fraction of a rotation or in two or more rotations. Limitation with pen recovery latency time is addressed through this technique.
In a second general embodiment, the rotation speed of the media may substantially exceed the print pen-firing rate such that the target sector passes several times under the pen-firing zone during any given radial position. In this situation, the print pen may fire at an angular position to optimize the placement of an ink dot onto the media at a rate commensurate with the firing frequency of the print pen. In this way, the print pen can place ink on the surface during any one of subsequent successive rotations, piecing the individual image elements together much like a patchwork quilt. This mechanism may be used to address radial printing limitations such as maximum pen frequency.
In a specific implementation, interlaced timing of all pen firing is directed by the feedback information from a rotary encoder and the pen controller.
In a specific embodiment, a method of printing onto a rotating media is disclosed. The media is rotated at a selected rotation speed. Ink is dispensed onto a first sector of a radial print track of the rotating media during a first rotation of the media. Ink is also dispensed onto a second sector of a radial print track of the rotating media during a second rotation of the media. The radial print track has a larger area than either the first sector or the second sector.
In a specific aspect, ink is dispensed onto a plurality of first sectors of the radial track of the rotating media during the first rotation of the media. In a further aspect, ink is dispensed onto a plurality of second sectors of the radial track of the rotating media during the second rotation of the media. In another specific implementation, the rotation speed is selected so that ink is dispensed onto a first sub-sector and not onto a second sub-sector of the first sector during the first rotation, and ink is dispensed onto the second sub-sector of the first sector during the second rotation. Additionally, the first sub-sector of the first sector is contiguous with the second sub-sector of the first sector. In a related implementation, the rotation speed is selected so that ink is dispensed onto a first sub-sector and not onto a second sub-sector of the second sector during the second rotation, and ink is dispensed onto the second sub-sector of the second sector during the first rotation. The first sub-sector of the second sector is also contiguous with the second sub-sector of the second sector.
In a specific implementation, the second rotation immediately follows the first rotation. In another aspect, a distance between the first and second sectors is equal to a duration of time required by an ink dispensement mechanism to recover after dispensing ink onto the first sector. In a preferred embodiment, the media is an optical recording media disc, such as a CD. In another implementation, the first and second sector are each an arch-shaped swath of a limited angular length on a surface of the rotating media
In an alternative embodiment, the invention pertains to a printing system for radially printing onto a rotating media The printing system generally includes a rotation mechanism for rotating the media at a selected rotation speed and a dispensement mechanism for dispensing ink onto a media while the media is rotating under the dispensement mechanism. The printing system further includes a controller for causing the dispensement mechanism to perform one or more of the above described method embodiments.